Fluid oscillator with feedback and pulsating shower head employing same

ABSTRACT

A fluid oscillator for producing pulsations in a flow of fluid, having a housing with a fluid inlet channel for connection with a supply of fluid under pressure, a fluid outlet channel, and a diaphragm valve which alternatively opens and closes causing intermittent flow of fluid from the fluid inlet channel to the fluid outlet channel. The valve opens due to the fluid supply pressure to allow fluid to flow through the fluid outlet channel. The valve then closes due to a reduction in fluid pressure in the fluid outlet channel resulting from the inertia of the fluid flowing through the fluid outlet channel. The reduction in pressure dissipates after the valve closes, at which time the fluid supply pressure again opens the valve to repeat the cycle. A feedback channel communicates with the valve and the fluid flowing through the housing so that movements in the valve ordinarily caused by variations in the fluid supply pressure are substantially offset by fluid pressure variations in the feedback channel. The valve has a pair of diaphragms defining a valve chamber therebetween, so that fluid entering the feedback channel is prevented from entering the valve chamber. A second fluid outlet channel may be connected to the fluid inlet channel upstream of the valve so that fluid flow is diverted to the second fluid outlet channel when the valve is closed.

United States Patent [191 Kwok Nov. 18, 1975 FLUID OSCILLATOR WITH FEEDBACK AND PULSATING SHOWER HEAD EMPLOYING SAME [75] Inventor: Clyde C. K. Kwok, Montreal,

Canada [73] Assignee: Edward V. Rippingille, .lr., Key

Largo, Fla.

[22] Filed: Aug. 29, 1974 g 21 Appl. No.: 501,735

Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerMichael Mar Attorney, Agent, or Firm-Rogers, Bereskin & Parr [57] ABSTRACT A fluid oscillator for producing pulsations in a flow of fluid, having a housing with a fluid inlet channel for connection with a supply of fluid under pressure, a fluid outlet channel, and a diaphragm valve which alternatively opens and closes causing intermittent flow of fluid from the fluid inlet channel to the fluid outlet channel. The valve opens due to the fluid supply pressure to allow fluid to flow through the fluid outlet channel. The valve then closes due to a reduction in fluid pressure in the fluid outlet channel resulting from the inertia of the fluid flowing through the fluid outlet channel. The reduction in pressure dissipates after the valve closes, at which time the fluid supply pressure again opens the valve to repeat the cycle. A feedback channel communicates with the valve and the fluid flowing through the housing so that movements in the valve ordinarily caused by variations in the fluid sup ply pressure are substantially olfset by fluid pressure variations in the feedback channel. The valve has a pair of diaphragms defining a valve chamber therebetween, so that fluid entering the feedback channel is prevented from entering the valve chamber. A second fluid outlet channel may be connected to the fluid inlet channel upstream of the valve so that fluid flow is diverted to the second fluid outlet channel when the valve is closed.

19 Claims, 4 Drawing Figures US. Patent Nov. 18, 1975 Sheet 1 of2 3,920,185

FIGK] FIG 2 U.S. Patent Nov. 18, 1975 Sheet 2 of2 3,920,185

FIG. 4

FLUID OSCILLATOR WITH FEEDBACK AND PULSATING SHOWER HEAD EMPLOYING SAME This invention relates to fluid oscillators capable of producing periodic pulsations in fluid flow, and in particular to a pulsating shower head employing the same. More specifically, the invention relates to a fluid oscillator in which a feedback channel is included to make the fluid oscillator relatively insensitive to variations in fluid supply pressure.

Fluid oscillators have been developed which utilize fluid dynamic effects such as stream interaction and boundary layer control to provide a pulsating flow of fluid without any moving parts. In practice such devices generally must be constructed with fairly close tolerances in order to achieve satisfactory results, and the cost of such devices is generally quite high.

An object of the present invention is to provide a relatively inexpensive fluid oscillator which is particularly adapted for use as a shower head or fixture and which is relatively insensitive to variations in fluid supply pressure.

A fluid oscillator according to the invention includes a housing having a fluid inlet channel for connection to a supply of fluid under pressure and a fluid outlet channel which communicates with the fluid inlet channel to allow fluid to flow through the housing. A valve is positioned so as to control the flow of fluid from the fluid inlet channel to the fluid outlet channel. The valve is operable by fluid pressure alternately to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel.

The valve opens due to the pressure of the fluid supply and it is biased toward the closed position. The fluid outlet channel is dimensioned so that when the valve reaches the open position, the flow of fluid in the fluid outlet channel produces a reduction in pressure in the fluid outlet channel which primarily causes the valve to close. This also creates a partial vacuum in the fluid outlet channel when the valve is closed, which vacuum holds the valve firmly in its closed position. The partial vacuum substantially dissipates after the valve closes. The fluid supply pressure then opens the valve again and the cycle is repeated resulting in oscillation of the valve from its closed to open position.

A feedback channel is connected between the valve and the fluid flowing through the housing so that a variation in the fluid supply pressure tending to vary the position of the valve causes a corresponding variation in the pressure in the feedback channel tending to substantially offset any variation in the position of the valve. Thus the position of the valve is relatively unaffected by supply pressure variations. and therefore the valve will oscillate over a reasonably wide range of fluid supply pressures without adjustment of the fluid oscillator.

The valve includes a valve chamber located adjacent to the feedback channel, so that fluid entering the feedback channel is prevented from entering the valve and interfering with the alternate movement of the valve from the open to closed positions.

If desired, a second fluid outlet channel may be connected to the fluid inlet channel upstream of the valve. Fluid flow in the first fluid outlet channel with the valve open is then diverted to the second fluid outlet channel when the valve is closed.

The fluid inlet channel in the vicinity of the junction with the second fluid outlet channel may also be shaped to form a fluid ejector. This causes a suction effect in the second fluid outlet channel when fluid is flowing through the first fluid outlet channel. When the valve closes, the flow of fluid in the first fluid outlet channel is then suddenly diverted to the second fluid outlet channel producing a water hammer" effect. or instantaneous pressure rise in fluid flow through the second fluid outlet channel. This instantaneous pressure rise results in a pulse of fluid flow in the second fluid outlet channel. When the valve opens. the suction effect is again produced to stop the fluid flow in the second fluid outlet channel.

A preferred embodiment of the invention will now be described by way of example. by reference to the accompanying drawings in which:

FIG. 1 is a sectional view of a preferred embodiment of a pulsating shower head employing a fluid oscillator according to the invention;

FIG. 2 is a bottom view partly broken away of the pulsating shower head shown in FIG. 1;

FIG. 3 is a sectional view of another embodiment of a pulsating shower head employing a fluid oscillator according to the invention; and

FIG. 4 is a sectional view of yet another embodiment of a pulsating shower head employing a fluid oscillator according to the invention;

Referring firstly to FIGS. 1 and 2, a fluid oscillator as employed in a pulsating shower head is generally indicated by reference numeral 10, and it includes a housing 12 having a top housing portion 12a, an upper central housing portion 12b, a central housing portion 12c. a lower central housing portion l2d and a bottom housing portion 12s. The top housing portion 12a is formed with an inlet channel M- which is connected to a supply pipe 16 carrying a supply of fluid under pressure. A nozzle 18 is centrally located in the top housing portion 12a with a central bore forming a throat 20 communicating with the inlet channel 14. A junction chamber 22 and an outlet channel 24 are formed from a central bore and a recessed slot respectively. when the top portion 12a is attached to the upper central housing portion 12b.

The upper central housing portion 12b is formed with a central bore to form a receiver 26. The throat 20, junction chamber 22 and receiver 26 from a fluid ejector, the operation of which will be described below. A valve inlet 28 is formed from another central bore in upper central housing portion [2b. The inlet channel 14, throat 20, junction chamber 22 and receiver 26 all communicate with one another and form the fluid inlet channel discussed below. A valve outlet 30 in the form of an annular recess in the upper central housing portion [2b, together with valve inlet 28 define an annular valve seat 32. Channels 34 and 36 are formed in the upper central housing portion 12b to communicate with the valve outlet 30 and outlet channel 24 respectively.

The central housing portion is formed with channels 38 and 40 to communciate with channels 34 and 36 respectively. A valve chamber 42 is formed by a central bore in the central housing portion 12c.

The lower central housing portion 12d is formed with channels 44 and 46 to communicate with channels 38 and 40 respectively. A feedback chamber 48 is formed in the lower central housing portion 12d by a central bore. An outlet chamber 50 in the lower central housing portion 12d is formed by another ccntral bore. A feedback channel 52 is connected between and communicates with the feedback chamber 48 and the outlet channel 50. A cross-over channel 54 is formed in the lower central housing portion 12d which is connected to and communicates with channel 44 and outlet chamber 50.

The bottom housing portion lZe is located in a central bore formed in the lower central housing portion 12d. A channel 56 and a central output chamber 58 are formed by respective upper and lower central bores in the bottom housing portion l2e. An outer output chamber 60 is formed by an annular recess in the bottom housing portion 12c. A channel 62 is formed in the bottom housing portion l2e to communicate with channel 46 and the outer output chamber 60.

A cap 64 is attached to the bottom housing portion 122 by screws 66. An inner set of shower jets 68 is formed by an inner ring of holes or orifices in the cap 64 to communicate with the central output chamber 58. An outer set of shower jets 70 is formed by an outer ring of holes or orifices in the cap 64 to communicate with the outer output chamber 60.

A thin flexible upper diaphragm 72 is positioned between the upper central housing portion 12b and the central housing portion 120. A lower diaphragm 74 is positioned between the central housing portion 120 and the lower central housing portion 12d. Holes 75 are formed in diaphragms 72, 74 to allow channels 34, 38 and 44 to communicate with one another. Holes 77 are also fomed in diaphragms 72, 74 to allow channels 36, 40 and 46 to communicate with one another. A spacer 76 is centrally located between upper and lower diaphragms 72, 74 and is preferably attached to diaphragms 72, 74 to form a diaphragm assembly. When the diaphragm assembly is in position, the valve chamber 42 in the central housing portion 12c becomes an annular chamber enclosed by the upper and lower diaphragms 72, 74, the spacer 76 and the wall of the valve chamber 42. The operation of this valve chamber is described below.

The valve in this embodiment includes the valve inlet 28, the annular valve seat 32, the valve outlet 30, diaphragms 72, 74, spacer 76 and valve chamber 42. Diaphragms 72, 74 can be formed of any resilient material capable of withstanding the maximum fluid pressure in the fluid inlet channel. Typical materials include neoprene and rubber. As will be explained in greater detail below, diaphragm 72 is movable between an open position wherein there is a small gap between diaphragm 72 and the annular valve seat 32, so that fluid is permitted to flow past the annular valve seat 32 into the valve outlet 30, and a closed position wherein the diaphragm 72 firmly engages the annular valve seat 32 to prevent fluid from flowing into the valve outlet 30.

The valve is biased by a spring 78. The upper end of spring 78 bears against a disc 80 which in turn bears againsst the lower diaphragm 74. A guide 82 holds the lower end of spring 78 in position. The guide 82 is mounted on a threaded rod 84 so that the guide 82 can be turned and moved along the threaded rod 84 to adjust the bias or force exerted by spring 78 on the valve. The threaded rod 84 is centrally located in a threaded hole 86 in the lower central housing portion 12d.

The first fluid outlet channel as discussed below includes the following communicating elements: the channels 34, 38 and 44, the cross-over channel 54, the outlet chamber 50, channel 56, the central output 4 chamber 58, and the inner set of jets 68. The second fluid outlet channel as discussed below includes the following communicating elements: the outlet channel 24, the channels 36, 40, 46 and 62, the outer output chamber 60, and the outer sets ofjets 70.

HO. 2 is a bottom view of fluid oscillator 10. The first quadrant of this view has been broken away to show bottom housing portion l2e which is normally located behind cap 64.

The operation of pulsating showerhead 10 commences when fluid under pressure enters the fluid inlet channel through supply pipe 16, and flows through throat 20, junction chamber 22 and receiver 26 to valve inlet 28. The valve commences to open under the pressure of the fluid supply and fluid commences to flow into the first fluid outlet channel beginning with the channel 34 and ending with the inner set of jets 68 as discussed above. At the same time, fluid in the junction chamber 22 enters the second fluid outlet channel beginning with the outlet channel 24 and ending with the outer set of jets as discussed above.

As the valve approaches its open position, flow in the first fluid outlet channel increases. As discussed above, the throat 20, junction chamber 22 and receiver 26 preferably form a fluid ejector. When fluid flows through the nozzle 18, a suction effect is created in the junction chamber 22 and the second fluid outlet channel. This suction effect reduces the pressure in the second fluid outlet channel which tends to stop the fluid flowing in the second fluid outlet channel.

When the valve reaches its open position, the force exerted on the upper diaphragm 72 by the fluid supply pressure is balanced by the force exerted on lower diaphragm 74 by spring 78. However, due to the inertia of the fluid flowing through the first fluid outlet channel maximum flow does not occur until after the valve reaches its open position. With the valve in its open position, an increasing fluid flow between annular valve seat 32 and upper diaphragm 72 causes a decrease in static fluid pressure at this point. This pressure decrease, coupled with the force exerted by spring 78 causes the valve to commence closing by the upper diaphragm 72 moving toward the annular valve seat 32. As the valve commences to close, the cross-sectional flow area between the diaphragm 72 and the annular valve seat 32 is decreased thereby reducing the fluid flowing into the first fluid outlet channel. However, the inertia of the fluid flowing in the first fluid outlet channel tends to maintain the original flow rate The result is a reduction in pressure in the first fluid outlet channel. This reduction in pressure aids in drawing upper diaphragm 72 toward the annular valve seat 32, which further reduces the flow, thereby increasing the pressure reduction Causing the valve to snap closed. When this happens, a partial vacuum is created in the first fluid outlet channel which holds upper diaphragm 72 firmly against the annular valve seat 32.

When the valve snaps closed, fluid which normally flows into the first fluid outlet channel is suddenly diverted to the second fluid outlet channel producing a water hammer" effect or instantaneous pressure rise in the second fluid outlet channel. Therefore the pressure in the second fluid outlet channel increases from a very low pressure to an instantaneous pressure which may be considerably higher than the fluid supply pressure. This results in a pulse of fluid flow in the second fluid outlet channel after which the pressure drops to a level corresponding to the fluid supply pressure.

After a predetermined interval, which depends primarily on the volume of the first fluid outlet channel, the partial vacuum in the first fluid outlet channel is substantially dissipated and the pressure in the first fluid outlet channel approaches ambient. At this time, the pressure of the fluid supply in the fluid inlet channel acting on the valve being greater than the force exerted on diaphragm 74 by the now extended spring 78, the valve commences to open once again. Fluid then commences to flow into the first fluid outlet channel, pressure is decreased in the second fluid outlet channel due to the suction effect in junction chamber 22 as described above, and the above cycle is repeated. The result is oscillation of the diaphragm assembly and alternate fluid flow pulses in the first and second fluid outlet channels.

The force exerted on the diaphragm 74 by the spring 78 may be adjusted by turning guide 82 to accommodate variations in supply pressure in various localities. When the valve reaches its open position due to the force of the fluid supply pressure, the spring 78 exerts a force which helps to close the valve, discussed above. If, for example, the fluid supply pressure in a certain locality is high, the force exerted by spring 78 may have to be increased to cause the diaphragm valve to close. When guide 82 is adjusted to allow the correct force to be exerted by spring 78, the valve will close and thus oscillate producing the desired pulsating flow. Also, by changing the compression of spring 78 by adjustment of guide 82, it is possible to vary the frequency of oscillation of the valve if this is desired.

It is not uncommon for water pressure in a house to vary rapidly over wide limits. Although it may be possible to adjust guide 82 to compensate for such variations, if they are of short duration, frequent adjustment of the guide 82 would be necessary and hence this would be undesirable. In order to make the shower head less sensitive to such supply pressure variations, feedback channel 52 is connected between the first fluid outlet channel and feedback chamber 48. When the fluid supply pressure increases, the pressure in the fluid inlet channel increases which is the pressure causing the valve to open. However, pressure in the first fluid outlet channel is also increased. Since the feedback channel 52 is connected to the first fluid outlet channel, fluid tends to enter the feedback channel 52. This causes a pressure increase in feedback chamber 48 exerting a force on diaphragm 74 and tending to close the valve. In this way an increase in the fluid supply pressure, which ordinarily tends to open the valve, is substantially offset by an increase in the pressure in feedback chamber 48, which ordinarily tends to close the valve. A similar compensating effect is achieved for a decrease in the fluid supply pressure. The result is that the pulsating shower head 10 is relatively unaffected by supply pressure variations since the oscillation of the valve is relatively insensitive to changes in supply pressure, Adjustment of the guide 82 is only necessary for major changes in the level of the fluid supply pressure.

it should be noted that too much feedback, which could result from the feedback channel 52 being too large, is not desirable. in this case amplitude and the sharpness" of fluid pulses in the fluid outlet channels may be reduced. Also, the orifices of the inner set of jets 68, which is the last element in the first fluid outlet channel, should not be too large in diameter. There should be sufficient restriction in the fluid flow through 6 the inner set of jets 68 to produce a back pressure in the first fluid outlet channel to divert some of the fluid into the feedback channel 52.

The first fluid outlet channel is dimensioned so that it has sufficient volume to produce the desired pressure reduction effect when the valve closes. This may be done by making the first fluid outlet channel of such length that the fluid flowing therein has sufficient inertia, as discussed above. The length of the first fluid outlet channel may be increased by forming several parallel channels in the housing 12 and connecting them at the top and bottom to form one long channel. The dimensions of the second fluid outlet channel are not especially critical. The dimensions of the throat 20, junction chamber 22 and the receiver 26 are such as to produce a maximum suction effect consistent with the minimum pressure drop across the ejector, The diame ter of the outer set of jets 70 may be varied in order to produce the desired output pressure.

Valve chamber 42 located between diaphragms 72, 74 provides a cushion between feedback chamber 48 and the fluid in the fluid inlet channel. Valve chamber 42 and feedback chamber 48 are normally filled with air when shower head 10 is assembled. This air cushion in valve chamber 42 prevents the valve from oscillating at undesirably high frequencies as discussed next below.

Shower head it) is normally used with liquid fluid supplies, such as water. For high liquid supply pressures (above 60 pounds per square inch), the liquid entering feedback channel 52 may absorb some of the air in outer output chamber 60. This may result over a period of time (several weeks of continued use), in the feed back chamber becoming filled with liquid. If valve chamber 42 were omitted from shower head 10 (by eliminating lower diaphragm 74) liquid on both sides of upper diaphragm 72 would be directly connected through a liquid path to the liquid supply. In this situation, the valve would oscillate at a frequency which is too high to produce the desired flow pulses in the fluid outlet channels. The air cushion in valve chamber 42 prevents the valve from oscillating at too high a frequency,

It will be appreciated from the foregoing description of this embodiment that structural variations may be made in this embodiment. For example, the bias of spring 78 may be adjusted externally by extending threaded rod 84 outside housing 12. Alternatively, guide 82 could be made to slide on rod 84 and another member could be provided to extend into housing 12 to move guide 82 axially along rod 84.

it may be convenient if the bias of spring 78 is adjusted externally, to enlarge guide 82 so that it covers feedback channel 52 when it is moved toward the shower jets. In this position, spring 78 would not exert enough force on diaphragm 74 to cause the valve to close and oscillate. The result would be similtaneous steady flow in both the first and second outlet channels, or a normal shower.

Reference is next made to H0. 3, wherein another embodiment ofa pulsating shower head is generally indicated by reference numeral 90. Shower head includes a housing 92 having a top housing portion 92a, an upper central housing portion 92);, a central housing portion 92c, a lower central housing portion 92d and a bottom housing portion 92e. The top housing portion is formed with an inlet channel 94 which is connected to a supply pipe 95 carrrying a supply of fluid under pressure. A conical reducer 96 and a throat 98 are also formed in the top housing portion 92a to communicate with the inlet channel 94 to form a nozzle. A junction chamber 100 is formed by a central bore in the top housing portion 92a, Left and right outlet channels 102 and 104 are formed from respective left and right recessed slots in the top housing portion 920 when the top housing portion 920 is attached to the upper central housing portion 92b.

The upper central housing portion 92b is formed with a central bore to form a receiver 106. The throat 98 junction chamber 100 and receiver 106 form a fluid ejector. the operation of which is discussed above. A valve inlet 108 is formed by another central bore in upper central housing portion 92b to communicate with receiver 106. The inlet channel 94, conical reducer 96, throat 98,junction chamber 100 and receiver 106 all communicate with one another and form the fluid inlet channel discussed below. A valve outlet 110 formed by an annular recess in upper central housing portion 92b together with valve inlet 108 define an annular valve seat 112. A channel 114 is formed in the upper central housing portion 92b to communicate with the valve outlet 110. Channels 116, 118 are also formed in the upper central housing portion 92b to communicate with respective left and right outlet channels 102, 104.

The central housing portion 92c is formed with channels 120, 122 and 124 to communicate with respective channels 116, 114 and 118. A valve chamber 126 is formed by an upper central bore 128 and a larger lower central bore 130 in the central housing portion 92c.

The lower central housing portion 92d is formed with a large upper central bore 132 threaded partially on the inside. so that on assembly the central housing portion 921' and the upper central housing portion 9217 can be placed inside the upper central bore 132 and the top housing portion 92a can be screwed into the lower central housing portion 92d to hold the above housing portions 92a. 92b, 92c. 92d together. The lower central housing portion 92d is also formed with a lower central bore 134 threaded partially on the inside, so that on assembly the bottom housing portion 92e can be screwed into the lower central housing portion 92d. An outer output chamber 136 is formed by an annular recess in the lower central housing portion 92d to communicate with channels 120, 124. An outer set of shower jets 138 is formed by an outer ring of holes or orifices in the lower central housing portion 92d to communicate with the outer output chamber 136. A channel 140 is formed in the lower central housing portion 92d to communicate with channel 122 and the lower central bore 134. A central bore 142 is also formed in the lower central housing portion 92d to communicate with the lower central bore 134.

The bottom housing portion 922 is formed with an upper conical recess 144 and a lower conical recess 146. The upper conical recess 144 communicates with the lower central bore 134 in the lower central housing portion 92d. An inner set of shower jets 148 is formed by an inner ring of holes or orifices in the bottom housing portion 92a which communicate with the upper conical recess 144. The upper conical recess 144, and the central bore 142 and lower central bore 134 in the lower central housing portion 92d. all communicate with one another to form a feedback chamber 149. The

lower conical recess 146 is open to the atmosphere.

An upper diaphragm 150 is positioned between the upper central housing portion 92b and the central housing portion 920. A lower diaphragm 152 is positioned between the central housing portion 92c and the lower central housing portion 92d. Holes 154 are formed in diaphragms 150, 152 to allow channels 116, and outer output chamber 136 to communicate with one another. Holes 155 are formed in diaphragms 150, 152 to allow channels 114, 122 and to communicate with one another. Holes 156 are formed in diaphragms 150, 152 to allow channels 118, 124 and outer output chamber 136 to communicate with one another. A spacer 158 is centrally located between upper and lower diaphragms 150, 152 and is preferably attached to diaphragms 150, 152 to form a diaphragm assembly. When the diaphragm assembly is in position the valve chamber 126 in the central housing portion 92c becomes an annular chamber enclosed by the upper and lower diaphragms 150, 152, the spacer 158 and the walls of the valve chamber 126. The operation of the valve chamber has been described above in the discussion of the first embodiment. Diaphragms 150, 152 are similar to diaphragms 72, 74 described above. The valve in this embodiment includes the valve inlet I08 annular valve seat 112, valve outlet 110, upper and lower diaphragms 150. 152 and spacer 158.

The first fluid outlet channel as discussed below includes the following communicating elements: the channels 114, 122 and 140, part of the pressure feedback chamber 149 and the inner set of jets 148. The second fluid outlet channel as discussed below includes the following communicating elements: the left and right outlet channels 102, 104; respective channels 116, 118 and 120, 124; the outer output chamber 136; and the outer set of jets 138.

The operation of the pulsating shower head 90 is very similar to the embodiment shown in FIGS. 1 and 2. When the valve is in its open position. fluid flowing in the fluid inlet channel is permitted to flow between the annular valve seat 112 and the upper diaphragm into the first fluid outlet channel. When the diaphragm valve is in its closed position, flow is diverted to the second fluid outlet channel producing a water hammer" effect resulting in a pulse of fluid flow in the second fluid outlet channel.

The main difference between this embodiment and the embodiment shown in FIGS. 1 and 2 is that the spring for biasing the valve has been eliminated. The surface area of lower diaphragm 152 which is in contact with the fluid in the feedback chamber 149, is larger than the surface area of the upper diaphragm 150 which is in contact with the fluid in the valve inlet 108 and the valve outlet 110. The result is that when the valve is open and fluid is flowing in the first fluid outlet channel, the upward force exerted on the lower diaphragm 152 becomes greater than the downward force exerted on the upper diaphragm 150, therefore the valve assembly is biased to close due to this net upward force or pressure differential.

As discussed above. as the valve opens, fluid flow in the first fluid outlet channel increases. This flow does not reach a maximum until after the valve reaches its open position. As the flow increases to a maximum with the diaphragm valve in the open position, there is a reduction in static fluid pressure between annular valve seat 112 and diaphragm 150. This reduction in pressure together with the bias caused by the differential pressure on the diaphragm assembly causes the valve to commence closing.

Once the valve commences to close. the pressure reduction and partial vacuum created in the first fluid outlet channel increase. as discussed above. which aid' in closing and hold the valve firmly in its closed position. With the valve closed, fluid is diverted to the sec ond fluid outlet channel. Again, once the partial vacuum in the first fluid outlet channel is substantially dissipated, the fluid pressure therein approaches ambient. At this time. the pressure in the fluid inlet channel causes the valve to commence opening again to repeat the pulsating cycle of the fluid oscillator.

Another difference between this embodiment and the embodiment shown in FIGS. 1 and 2 is that a separate feedback channel has been eliminated. A feedback system is automatically incorporated into the first fluid outlet channel in this embodiment. An increase in fluid supply pressure, which normally would cause the valve to open. also causes a proportionate increase in the pressure in the first fluid outlet channel and the feedback chamber. Since an increase in the pressure in the feedback chamber tends to cause the valve to close. the result is that the movement of the valve is substantially unaffected by supply pressure variations. The shower head shown in FIG. 3 is therefore relatively insensitive to fluid supply pressure variations.

As in the embodiment shown in FIG. 1, the annular valve chamber [26 between the upper and lower diaphragms 150, 152 prevents the valve from oscillating at a frequency which is too high to produce the desired pulses in the fluid outlet channels. As discussed above, the first fluid outlet channel is dimensioned so that it will produce the desired pressure reduction when flow is decreased as the valve closes. If it is necessary to increase the length of the first fluid outlet channel to produce this pressure reduction, annular recesses may be formed in one or more of the housing portions which may be interconnected to form one long channel.

Referring next to FIG. 4, another embodiment of a pulsating shower head is generally indicated by reference numeral 160. Shower head 160 is similar to the embodiments shown in FIGS. 1 and 3 except that shower head 160 has only one fluid outlet channel as opposed to first and second fluid outlet channels. The

' operation of shower head 160 is similar to the embodiments shown in FIGS. 1 and 3 when the second fluid outlet channel of the latter embodiments has been blocked or eliminated as described below.

Shower head 160 includes a housing 162 having a top housing portion 162a, a central housing portion l62b and a bottom housing portion 162:. The top housing portion 1620 is formed with an inlet channel 164 which is connected to a supply pipe 166 carrying a supply of fluid under pressure. An outlet channel I68 is formed in top housing portion 162a to communicate with inlet channel 164. It will be noted that there is no fluid ejector formed in shower head 160 as in the previously described embodiments, because the second fluid outlet channel has been eliminated in shower head 160.

Top housing portion [62a also includes a valve inlet 170 formed by a central bore to communicate with fluid inlet channel 164. An annular recess forms a valve outlet 172 which together with valve inlet [70 define an annular valve seat 174. A channel 176 is formed in top housing portion 162a to communicate with valve outlet 172.

The central housing portion l62h is formed with channels I78, 180 to communicate with respective channel 176 and outlet channel 168. A valve chamber 181 is formed by an upper central bore 182 and a smaller lower central bore 184 in central housing portion l62b. A vent 186 is formed by a hole through central housing portion l62b so that valve chamber 181 communicates with the atmosphere outside shower head 160.

The bottom housing portion l62c has a feedback chamber 188 in the form of a central bore. A channel 190 is formed in bottom housing portion 1620 to communicate with feedback chamber 188. An output chamber 192 is formed by an annular recess in bottom housing portion 162( and a channel 194 is formed therein to communicate with output chamber 192.

A cap 196 is attached to bottom housing portion 1626 by a screw 198. A set of shower jets 200 is formed in the cap 196 by a ring of holes or orifices which communicate with output chamber 192.

An upper diaphragm 202 is positioned between the top housing portion 162a and the central housing portion l62b. A lower diaphragm 204 is positioned between central housing portion l62b and bottom housing portion 162C. Holes 206 are formed in diaphragm 202, 204 to allow channels 176, 178 and 194 to communicate with one another. Holes 208 are also formed in diaphragms 202, 204 to allow outlet channel 168 and channels [80, 190 to communicate with one another. A spacer 210 is centrally located between upper and lower diaphragms 202, 204 and is preferably attached to diaphragms 202, 204 to form a diaphragm assembly. When the diaphragm assembly is in position the valve chamber 18] becomes a generally annular chamber enclosed by the upper and lower diaphragms 202, 204, the spacer 210 and the walls of the valve chamber 181. The operation of the valve chamber has been described above. Diaphragms 202, 204 are similar to diaphragms 72, 74 (FIG. I) described above. The valve in this embodiment includes the valve inlet 170. the annular valve seat 174, the valve outlet 172 upper and lower diaphragms 202, 204 and spacer 210.

There is only one fluid outlet channel in this embodiment and it includes channels 176, 178, I94, output chamber 192 and the set of shower jets 200. The dimensions of the fluid outlet channel are similar to those of the first fluid outlet channels discussed above. The feedback channel in this embodiment includes outlet channel 168 and channels 180, 190.

The operation of shower head 160 is somewhat similar to that of the embodiments previously described. As fluid enters inlet channel I64 the valve opens and fluid flows through the fluid outlet channel. This flow reaches a maximum after the valve reaches its open position. An increasing fluid flow with the valve in the open position causes a reduction in static fluid pressure between annular valve seat 174 and diaphragm 202. This pressure reduction together with the fluid pressure in feedback chamber 188 causes the valve to commenee closing. When the valve commences to close, the pressure reduction and partial vacuum created in the fluid outlet channel increase, as discussed above, which help the valve to snap closed and remain firmly closed. When the partial vacuum in the fluid outlet channel is substantially dissipated. the fluid pressure in the fluid inlet channel causes the valve to commence opening again to repeat the pulsating cycle of the shower head.

It will be appreciated that the feedback channel in shower head I60 makes shower head I60 relatively insensitive to fluid supply pressure variations. An increase in fluid supply pressure. which normally would cause the valve to open. also causes an increase in the fluid pressure in feedback chamber 188. Since an in crease in the pressure in feedback chamber I88 tends to cause the valve to close. the result is that the movement of the valve is substantially unaffected by supply pressure variations.

Outlet channel I68 and channels I80, 190 form the feedback channel in this embodiment. Since feedback results directly from the fluid supply, this type of feedback could be called a positive feedback or a feedforward.

It will be noted that there is no spring in shower head I60 to bias the valve toward a closed position. The pressure of the fluid in feedback chamber I88, which is substantially the same as the fluid supply pressure, biases the valve to close.

It should also be noted that the area of diaphragm 202 which is adjacent to valve inlet I70 is larger than the area of diaphragm 204 adjacent to feedback chamber I88. The reason for this is that in order for the shower head to commence oscillating easily, the downward force on the valve caused by fluid pressure in valve inlet I70 should be greater than the upward force on the valve caused by fluid pressure in feedback chamber 188.

It will be evident from the foregoing description of preferred embodiments of the invention, that variations may be made in each embodiment. In the embodiment shown in FIG. I, the second fluid outlet channel may be blocked or eliminated. The first fluid outlet channel would then be the only fluid outlet channel. The fluid ejector formed by throat 20, junction chamber 22 and receiver 26 could then also be eliminated and replaced by a straight fluid inlet channel. Fluid flowing in the fluid outlet channel with the valve open would simply stop flowing through the shower head when the valve closed. A single set of shower jets 68 would provide a pulsating or intermittent fluid flow rather than alternate pulsating flow between inner and outer sets of jets 68, 70.

Feedback channel 52 could be relocated to communicate with the fluid inlet channel or the fluid supply if desired. In this case there would be a pressure feed forward or positive feedback rather than a pressure feedback in the strict sense, like the embodiment shown in FIG. 4. However. it will be understood that the term feedback in this specification is intended to include both the feedback and the feed forward situation.

If the feedback channel is located to communicate with the fluid supply in the embodiment shown in FIG. I it would be preferable to dimension valve inlet 28 or the feedback chamber 48 so that the area of upper diaphragm 72 adjacent to valve inlet 28 is larger than the area of lower diaphragm 74 adjacent to feedback chamber 48. The reason for this is that if feedback chamber 48 becomes filled with fluid, the differential in area will ensure that the downward force on diaphragm 72 caused by fluid pressure in valve inlet 28 will be greater than the upward force on diaphragm 74 caused by fluid pressure in feedback chamber 48. This downward force should be greater than the upward force in order for shower head I0 to commence oscillating easily when fluid pressure is supplied to fluid inlet channel 14.

The embodiment shown in FIG. 3 may also be varied by blocking or eliminating the second fluid outlet channel. The considerations for operating this embodiment with a single fluid outlet channel are the same as discussed above. If desired. additional bias means may be added to the FIG. 3 embodiment in the form of an adjustably tensioned spring acting on the diaphragm assembly. This would enable this embodiment to be ad justed to oscillate at different frequencies and also to operate in the steady flow mode.

The embodiment shown in FIG. 4 may be varied by adding additional bias means such as an adjustable spring acting on the diaphragm assembly. This would permit variation of the frequency of oscillation and a steady flow mode as discussed above. Vent 186 may be blocked or eliminated if desired. in order to improve the air cushion effect in valve chamber I81 as discussed above.

In all three embodiments the spacer between the diaphragms may be eliminated if desired. However, the upper diaphragm may not close tightly against the annular valve seat so that the efficiency of the fluid oscillator may decrease.

Throughout the present specification, reference is made to the term fluid". As employed in a pulsating shower head, the fluid oscillator of the present invention is intended to operate with water. However, any fluid of sufflcient density to achieve the required pressure reduction effect in the first fluid outlet channel may be used. In particular, the fluid oscillator of the present invention is intended to operate at a relatively low frequency and to produce pulsations in the flow of liquid. Also. in all of the embodiments described in the present specification, a diaphragm type valve has been employed. It will be appreciated that any other type of valve may be employed which has the required characteristics. In particular a piston may be substituted for a diaphragm if the fluid supply pressure is adequate to compensate for friction losses.

What I claim is:

I. A fluid oscillator for producing pulsations in a flow of fluid comprising:

a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing;

b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the fluid outlet channel, the valve means being operable by fluid pressure alternately to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel;

c. the valve means including a valve inlet communicating with the fluid inlet channel, a valve outlet communicating with the fluid outlet channel and means to bias the valve means toward a closed position, the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet;

d. the fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the field outlet channel when the valve means reaches the closed position. the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open;

. the housing defining a feedback channel communieating with valve means and with the fluid flowing through the housing, so that a variation in the fluid supply pressure tending to vary the position of the valve means causes a corresponding variation in pressure in the feedback channel tending to substantially offset any variation in the position of the valve means; and the valve means including separating means defining a valve chamber adjacent to the feedback channel. the separating means being positioned so that fluid entering the feedback channel is prevented by the separating means from entering said valve chamber.

2. A fluid oscillator as claimed in claim 1 wherein the valve means further includes a valve seat located between the valve inlet and the valve outlet, and a diaphragm located adjacent to the valve inlet and between the valve seat and said valve chamber; the diaphragm being movable so that when the valve means is in the open position the diaphragm is spaced from the valve seat to permit fluid flow from the valve inlet to the valve outlet. and so that when the valve means is in the closed position the diaphragm is positioned against the valve seat to prevent fluid flow from the valve inlet to the valve outlet.

3. A fluid oscillator as claimed in claim 2 wherein the diaphragm is a first diaphragm and wherein the separating means comprises a second diaphragm spaced from the first diaphragm; said valve chamber being located between the first and second diaphragms; and wherein the feedback channel includes a feedback chamber located adjacent to the second diaphragm.

4. A fluid oscillator as claimed in claim 3 wherein the feedback channel communicates with the fluid outlet channel.

5. A fluid oscillator as claimed in claim 3 wherein the feedback channel communicates with the fluid inlet channel, and wherein the surface area of the first diaphragm exposed to the fluid in the valve inlet is larger than the surface area of the second diaphragm exposed to the feedback chamber.

6. A fluid oscillator as claimed in claim 2 wherein the fluid outlet channel is a first fluid outlet channel, and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that the fluid flowing through said first fluid outlet channel with the valve means open is diverted to the second fluid outlet chan nel when the valve means is closed.

7. A fluid oscillator as claimed in claim 6 wherein the diaphragm is a first diaphragm and wherein the separating means comprises a second diaphragm spaced from the first diaphragm; said valve chamber being located between the first and second diaphragms; and wherein the feedback channel includes a feedback channel located adjacent to the second diaphragm.

8. A fluid oscillator as claimed in claim 7 wherein said bias means comprises a spring located in the housing to apply a force on the valve means.

9. A fluid oscillator as claimed in claim 8 wherein the spring exerts a force on the second diaphragm, and further comprising means for adjusting said bias means.

10. A fluid oscillator as claimed in claim 9 wherein the feedback channel communicates with the first fluid outlet channel.

11. A fluid oscillator as claimed in claim 10 wherein the fluid inlet channel is shaped to form a fluid ejector at the connection with the second fluid outlet channel.

12. A fluid oscillator for producing pulsations in a flow of fluid comprising:

a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing;

b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow offluid between the fluid inlet channel and the fluid outlet channel. the valve means being operable by fluid pressure alternatively to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel;

c. the housing defining a feedback chamber in the fluid outlet channel adjacent to the valve means;

d. the valve means including a valve inlet communicating with the fluid inlet channel; a valve outlet communicating with the fluid outlet channel, a valve seat positioned between the valve inlet and the valve outlet, a pair of diaphragms spaced apart to define a valve chamber therebetwecn. a first one of said diaphragms being positioned across the valve seat and movable so that when the the valve means opens the first diaphragm is spaced from the valve seat so that fluid is permitted to flow from the valve inlet to the valve outlet and so that when the valve means is in a closed position the first dia phragm is positioned against the valve seat so that the fluid is prevented from flowing from the valve inlet to the valve outlet. a second one of the diaphragms being positioned adjacent to said feedback chamber so that the surface area of the sec ond diaphragm exposed to the fluid is larger than the surface area of the first diaphragm exposed to the fluid;

e. the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet; and the fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the fluid outlet channel when the valve means reaches the closed position. the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open,

13. A fluid oscillator as claimed in claim 12 wherein the fluid outlet channel is a first fluid outlet channel. and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed.

14. A fluid oscillator as claimed in claim 13 wherein the fluid inlet channel is shaped to form a fluid ejector at the connection with the second fluid outlet channel.

15. A pulsating shower head comprising:

a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing;

b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the fluid outlet channel. the valve means being operable by fluid pressure alternatively to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel;

c. the valve means including a valve inlet communicating with the fluid inlet channel. a valve outlet communicating with the fluid outlet channel and means to bias the valve means toward a closed position. the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet;

d. the fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the fluid outlet channel when the valve means reaches the closed position, the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open;

e. the housing defining a feedback channel communicating with valve means and with the fluid flowing through the housing. so that a variation in the fluid supply pressure tending to vary the position of the valve means causes a corresponding variation in pressure in the feedback channel tending to substantially offset any variation in the position of the valve means;

the valve means including a valve seat located between the valve inlet and the valve outlet, a first diaphragm located adjacent to the valve inlet and the valve seat. the first diaphragm being movable so that when the valve means is open the first diaphragm is spaced from the valve seat and when the valve means is closed the first diaphragm is positioned against the valve seat, and a second diaphragm spaced from the first diaphragm to define a valve chamber therebetween;

g. the feedback channel including a feedback chamber located adjacent to the second diaphragm; and

h. the housing defining a plurality of orifices in the fluid outlet channel to form a plurality of shower jets when fluid flows through the fluid outlet channel.

16. A pulsating shower head as claimed in claim 15 wherein the feedback channel communicates with the fluid outlet channel.

l7. A pulsating shower head as claimed in claim 15 wherein the fluid outlet channel is a first fluid outlet channel. and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed.

l6 18. A pulsating shower head as claimed in claim 15 wherein the feedback channel communicates with the fluid inlet channel. and wherein the surface area of the first diaphragm exposed to the fluid in the valve inlet is larger than the surface area of the second diaphragm exposed to the feedback chamber.

19. A pulsating shower head comprising:

a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure, and first and second fluid outlet channels for flow of fluid through the housing;

b. valve means positioned between the fluid inlet channel and the first fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the first fluid outlet channel, the valve means being operable by fluid pressure alternately to open and to close and thereby respectively to permit and to prevent fluid from flowing through said first fluid outlet channel;

c. the second fluid outlet channel being connected to communicate with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed;

d. the housing defining a feedback chamber in the first fluid outlet channel adjacent to the valve means;

e. the valve means including a valve inlet communieating with the fluid inlet channel, a valve outlet communicating with the first fluid outlet channel. a valve seat positioned between the valve inlet and the valve outlet. a pair of diaphragms spaced apart to define a valve chamber therebetween. a first one of said diaphragms being positioned across the valve seat and movable so that when the valve means opens said first diaphragm is spaced from the valve seat so that fluid is permitted to flow from the valve inlet to the valve outlet and so that when the valve means is in a closed position said first diaphragm is positioned against the valve seat so that fluid is prevented from flowing from the valve inlet to the valve outlet, and a second one of said diaphragms being positioned adjacent to said feedback chamber so that the surface area is larger than the surface area of the first diaphragm exposed to the fluid;

f. the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet;

g. the first fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in said first fluid outlet channel when the valve means reaches the closed position. the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open; and

h. the housing defining a plurality of orifices in the first and second fluid outlet channels to form a plurality of shower jets when fluid flows through the first and second outlet channels.

s a a: s 

1. A fluid oscillator for producing pulsations in a flow of fluid comprising: a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing; b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the fluid outlet channel, the valve means being operable by fluid pressure alternately to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel; c. the valve means including a valve inlet communicating with the fluid inlet channel, a valve outlet communicating with the fluid outlet channel and means to bias the valve means toward a closed position, the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet; d. the fluid outlet channel being dimensioned to produce a reduction in pressUre in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the field outlet channel when the valve means reaches the closed position, the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open; e. the housing defining a feedback channel communicating with valve means and with the fluid flowing through the housing, so that a variation in the fluid supply pressure tending to vary the position of the valve means causes a corresponding variation in pressure in the feedback channel tending to substantially offset any variation in the position of the valve means; and f. the valve means including separating means defining a valve chamber adjacent to the feedback channel, the separating means being positioned so that fluid entering the feedback channel is prevented by the separating means from entering said valve chamber.
 2. A fluid oscillator as claimed in claim 1 wherein the valve means further includes a valve seat located between the valve inlet and the valve outlet, and a diaphragm located adjacent to the valve inlet and between the valve seat and said valve chamber; the diaphragm being movable so that when the valve means is in the open position the diaphragm is spaced from the valve seat to permit fluid flow from the valve inlet to the valve outlet, and so that when the valve means is in the closed position the diaphragm is positioned against the valve seat to prevent fluid flow from the valve inlet to the valve outlet.
 3. A fluid oscillator as claimed in claim 2 wherein the diaphragm is a first diaphragm and wherein the separating means comprises a second diaphragm spaced from the first diaphragm; said valve chamber being located between the first and second diaphragms; and wherein the feedback channel includes a feedback chamber located adjacent to the second diaphragm.
 4. A fluid oscillator as claimed in claim 3 wherein the feedback channel communicates with the fluid outlet channel.
 5. A fluid oscillator as claimed in claim 3 wherein the feedback channel communicates with the fluid inlet channel, and wherein the surface area of the first diaphragm exposed to the fluid in the valve inlet is larger than the surface area of the second diaphragm exposed to the feedback chamber.
 6. A fluid oscillator as claimed in claim 2 wherein the fluid outlet channel is a first fluid outlet channel, and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that the fluid flowing through said first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed.
 7. A fluid oscillator as claimed in claim 6 wherein the diaphragm is a first diaphragm and wherein the separating means comprises a second diaphragm spaced from the first diaphragm; said valve chamber being located between the first and second diaphragms; and wherein the feedback channel includes a feedback channel located adjacent to the second diaphragm.
 8. A fluid oscillator as claimed in claim 7 wherein said bias means comprises a spring located in the housing to apply a force on the valve means.
 9. A fluid oscillator as claimed in claim 8 wherein the spring exerts a force on the second diaphragm, and further comprising means for adjusting said bias means.
 10. A fluid oscillator as claimed in claim 9 wherein the feedback channel communicates with the first fluid outlet channel.
 11. A fluid oscillator as claimed in claim 10 wherein the fluid inlet channel is shaped to form a fluid ejector at the connection with the second fluid outlet channel.
 12. A fluid oscillator for producing pulsations in a flow of fluid comprising: a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing; b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the fluid outlet channel, the valve means being operable by fluid pressure alternatively to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel; c. the housing defining a feedback chamber in the fluid outlet channel adjacent to the valve means; d. the valve means including a valve inlet communicating with the fluid inlet channel; a valve outlet communicating with the fluid outlet channel, a valve seat positioned between the valve inlet and the valve outlet, a pair of diaphragms spaced apart to define a valve chamber therebetween, a first one of said diaphragms being positioned across the valve seat and movable so that when the the valve means opens the first diaphragm is spaced from the valve seat so that fluid is permitted to flow from the valve inlet to the valve outlet and so that when the valve means is in a closed position the first diaphragm is positioned against the valve seat so that the fluid is prevented from flowing from the valve inlet to the valve outlet, a second one of the diaphragms being positioned adjacent to said feedback chamber so that the surface area of the second diaphragm exposed to the fluid is larger than the surface area of the first diaphragm exposed to the fluid; e. the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet; and f. the fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the fluid outlet channel when the valve means reaches the closed position, the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open.
 13. A fluid oscillator as claimed in claim 12 wherein the fluid outlet channel is a first fluid outlet channel, and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed.
 14. A fluid oscillator as claimed in claim 13 wherein the fluid inlet channel is shaped to form a fluid ejector at the connection with the second fluid outlet channel.
 15. A pulsating shower head comprising: a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure and a fluid outlet channel for flow of fluid through the housing; b. valve means positioned between the fluid inlet channel and the fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the fluid outlet channel, the valve means being operable by fluid pressure alternatively to open and to close and thereby respectively to permit and to prevent fluid from flowing through the fluid outlet channel; c. the valve means including a valve inlet communicating with the fluid inlet channel, a valve outlet communicating with the fluid outlet channel and means to bias the valve means toward a closed position, the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet; d. the fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in the fluid outlet channel when the valve means reaches the closed position, the partial vacuum substantially Dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open; e. the housing defining a feedback channel communicating with valve means and with the fluid flowing through the housing, so that a variation in the fluid supply pressure tending to vary the position of the valve means causes a corresponding variation in pressure in the feedback channel tending to substantially offset any variation in the position of the valve means; f. the valve means including a valve seat located between the valve inlet and the valve outlet, a first diaphragm located adjacent to the valve inlet and the valve seat, the first diaphragm being movable so that when the valve means is open the first diaphragm is spaced from the valve seat and when the valve means is closed the first diaphragm is positioned against the valve seat, and a second diaphragm spaced from the first diaphragm to define a valve chamber therebetween; g. the feedback channel including a feedback chamber located adjacent to the second diaphragm; and h. the housing defining a plurality of orifices in the fluid outlet channel to form a plurality of shower jets when fluid flows through the fluid outlet channel.
 16. A pulsating shower head as claimed in claim 15 wherein the feedback channel communicates with the fluid outlet channel.
 17. A pulsating shower head as claimed in claim 15 wherein the fluid outlet channel is a first fluid outlet channel, and wherein the housing further defines a second fluid outlet channel communicating with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed.
 18. A pulsating shower head as claimed in claim 15 wherein the feedback channel communicates with the fluid inlet channel, and wherein the surface area of the first diaphragm exposed to the fluid in the valve inlet is larger than the surface area of the second diaphragm exposed to the feedback chamber.
 19. A pulsating shower head comprising: a. a housing defining a fluid inlet channel adapted to be connected to a supply of fluid under pressure, and first and second fluid outlet channels for flow of fluid through the housing; b. valve means positioned between the fluid inlet channel and the first fluid outlet channel for controlling the flow of fluid between the fluid inlet channel and the first fluid outlet channel, the valve means being operable by fluid pressure alternately to open and to close and thereby respectively to permit and to prevent fluid from flowing through said first fluid outlet channel; c. the second fluid outlet channel being connected to communicate with the fluid inlet channel upstream of the valve means so that fluid flowing through the first fluid outlet channel with the valve means open is diverted to the second fluid outlet channel when the valve means is closed; d. the housing defining a feedback chamber in the first fluid outlet channel adjacent to the valve means; e. the valve means including a valve inlet communicating with the fluid inlet channel, a valve outlet communicating with the first fluid outlet channel, a valve seat positioned between the valve inlet and the valve outlet, a pair of diaphragms spaced apart to define a valve chamber therebetween, a first one of said diaphragms being positioned across the valve seat and movable so that when the valve means opens said first diaphragm is spaced from the valve seat so that fluid is permitted to flow from the valve inlet to the valve outlet and so that when the valve means is in a closed position said first diaphragm is positioned against the valve seat so that fluid is prevented from flowing from the valve inlet to the valve outlet, and a second one of said diaphragms being positioned adjacent to said feedback chamber so that the surface area is larger than the surface area of the first diaphRagm exposed to the fluid; f. the valve means being operable to open to an open position upon applying fluid pressure to the valve inlet and further urged toward a closed position when in the open position by a reduction in fluid pressure at the valve outlet; g. the first fluid outlet channel being dimensioned to produce a reduction in pressure in the fluid flowing therethrough after the valve means reaches the open position and also a partial vacuum in said first fluid outlet channel when the valve means reaches the closed position, the partial vacuum substantially dissipating after the valve means has reached the closed position resulting in the valve means again commencing to open; and h. the housing defining a plurality of orifices in the first and second fluid outlet channels to form a plurality of shower jets when fluid flows through the first and second outlet channels. 